Permanent magnet alternators are very compact compared to asynchronous generators and allow simplified mechanical integration thanks to being direct-driving by the rotor.

Permanent Magnet Alternators for Wind Turbines

Contributed by | Wind Simplicity

What are the advantages of Permanent Magnet alternators in wind applications? 

  • Direct drive (No speed multiplier, no gearbox needed)
  • Virually no maintenance
  • Highest power-to-weight ratio in direct drive
  • High efficiency
  • Simplification of mechanical design
  • Easy mechanical interface
  • Cost optimization

Wind turbines were typically equipped with asynchronous generators requiring to multiply the speed of rotor in order to produce the desired electrical power. Permanent magnet alternators are very compact compared to asynchronous generators and allow simplified mechanical integration thanks to being direct-driving by the rotor.  The efficiency of permanent magnet synchronous alternators is higher than that of asynchronous generators.

Wind turbine applications are growing – the cost of 1 kW per hour produced by wind is the cheapest of renewable energies

What types of Permanent Magnet alternators are available? 

The STK alternator is a brushless, synchronous, radial-flux design.

We can supply Permanent Magnet Alternators up to 95 kW; and Permanent Magnet brushless high-torque alternators with high-torque-to-weight ratio and low inertia loads (STK). The Permanent Magnet alternators are available either framed or frameless; the frameless devices are supplied as a paired stator and rotor. They require additional components and assembly.

  • Power range from 200 W up to 95 kW depending on size and speeds.
  • Speeds from 80 RPM up to 1500 RPM.
  • Six overall diameters from 145 mm up to 795 mm.
  • Internal diameter from 56 mm up to 630 mm.
  • 480V AC, tri-phase voltage at rated speed

The range of STK AC frameless permanent magnet generators includes 6 sizes from 145 mm up to 800 mm available in four different lengths per size and two standard rated speeds. Their extremely compact design and high efficiency allow the use in direct-drive small wind turbines, low power hydro generation and any other custom application that requires high-efficiency power generation.

What is the difference between a framed and unframed PM alternator? 

PMAs can be delivered as an unassembled stator and rotor, for integration into a design; they cannot be used as supplied.  However designed and manufactured parts assembled with the stator and rotor will create a fully functional, ready-to-use electrical generator that can be driven by the  driver of choice.

Paired rotor and stator Frame and assembly as supplied by 
Wind Simplicity™

Are they easy to frame? 

It is not difficult to design and manufacture a frame/housing and turn an unframed alternator into a fully functional power generator. What is required is engineering expertise, design and manufacture of parts, and assembly. Specialized tools are required for assembly, however, and safety is paramount when handling powerful permanent magnets. 

How are they framed? 

In order to use the PMAs, one needs to build them into functioning machines; they can be integrated into a larger design, or into a custom-built housing suitable for a particular application.

What other types of applications can they be used for? 

The STK alternators are suitable for any small energy generation application, such as small wind, small hydro, diesel generation, energy recovery or any other electricity generating application that requires a high-efficiency, low-maintenance energy source.

Please tell us a little about Wind Simplicity and your activity in the wind energy industry?

Wind Simplicity™ is the designer, manufacturer and turn-key installer of the high-efficiency, compact, noise-free (negligible noise/vibration) Windancer™ that helps save the environment by turning pollution-free wind energy into free electricity. A portable horizontal-axis small wind turbine, with a sustainable life cycle, the Windancer™ (3 kW and 7 kW) is ideal for generating energy onsite where there are good wind resources. Wind Simplicity™ also offers engineering services including PM alternator and motors and the framing of those, design and manufacture, and project management. 

How is business these days and how does the immediate future look for the wind energy industry?

Despite the economic downturn business has the potential to grow a lot more with government policy support for renewable energy that includes small wind turbines, conservation and grid modernization. The benefits of this will be local job creation and energy security. Small wind turbines that generate energy close to the consumer are a form of energy conservation. Renewable energy is cost-competitive, reliable compared to non-renewables and vital to protect the environment for our survival. 

Which products or services are you seeing the most activity in?

In terms of small wind turbines, we're seeing interest in off-grid, and off-setting higher grid rates. Higher priced electricity generates interest in conservation and reducing consumption from the grid. Visible green energy provided by an attractive small wind turbine is a dynamic advertizing for companies to show they are leaders in Corporate Social Responsibility and the triple bottom line (People, Planet,  Profit). Companies are finding that adopting green practices improves their triple bottom line. Investors are assured that the company is reducing their exposure to risks.

Do you think there are still new technologies to be developed for the wind energy industry or are we at the stage of incremental improvements and efficiency gains?

Both. A wind turbine is a system that involves several engineering areas of expertise, and there is room for incremental improvements and efficiency gains. These will be gained over time, not as fast as smart phone but more like the auto industry, and these gains will also trigger greater efficiencies in other systems as well. It's an exciting time. 

Do you have any other products or services that you are working on that can be talked about at this time?

We offer customized framing of permanent magnet motors, as well as the alternators. The motors offer greater efficiencies in servo-mechanical systems and, like the alternators, the advantages include higher efficiency, cost optimization, lower-maintenance operation and compact size. Both the motors and the alternators can be used in factory automation, exercise bikes, micro-grids, energy recovery systems, electric cars, forklift battery charging, cellular towers, traffic lights and more. 

Wind Simplicity™ is also working on new technology – “a converter” to make the power electronics more efficient. 

Renewable energy has brought in other forms of efficiency, and it's worthwhile to have a "before" and "after" record to show governments and shareholders. We also offer an easy benchmark cloud computing system that is sophisticated but simple to use, which helps companies uncover hidden wasted resources as well as opportunities for cost reduction and tracks the savings. 

The content & opinions in this article are the author’s and do not necessarily represent the views of AltEnergyMag

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